We investigate local acceleration dynamics of electrons with a new numerical simulation method, which is an extension of a world-leading kinetic plasma simulation. We describe how large supercomputer simulations can be used to initialize the electron simulations, and show numerical stability for the electron method. We briefly show that features of our simulated electrons match observations from Earth's magnetic tail region.

The atmospheric impacts of energetic particle precipitation (EPP) can be useful in understanding the uncertainties of measuring the precipitation. Hence information on how strong of an EPP flux has observable atmospheric impacts is needed. In this study we find such threshold flux values using odd hydrogen concentrations from both satellite observations and model simulations. We consider effects of solar proton events and radiation belt electron precipitation in the middle atmosphere.

Long and short period oscillations in the lunar semidiurnal tidal amplitudes in the ionosphere derived from the total electron content were investigated over Brazil from 2011 to 2014. The results showed annual, semiannual and intra-seasonal as the dominant components. Additionally, The most pronounced short period oscillation was the 7–11 days which presented characteristics compatible with the quasi 10 days planetary wave, suggesting a possible coupling process from the lower atmosphere.

We investigate the dynamics of helium in the foreshock, a part of near-Earth space found upstream of the Earth's bow shock. We show how the second-most common ion in interplanetary space reacts strongly to plasma waves found in the foreshock. Spacecraft observations and supercomputer simulations together give us new understanding of the foreshock edge and how to interpret future observations.

Travelling ionospheric disturbances behave like waves in the ionosphere, the ionised upper part of the atmosphere. In this study, we use an ionospheric tomography technique to map the electron content as affected by the passage of a large scale travelling ionospheric disturbance launched during the largest geomagnetic storm observed by modern instruments. This is the first such imaging using this software and to the authors' knowledge the first study of this travelling ionospheric disturbance.

We present a study of ultra-low-frequency waves in the ionosphere and on the ground. These waves are very slow (their periods are about several minutes). They are registered on the ground as geomagnetic pulsations. No simple dependence exists between geomagnetic and ionospheric pulsations. Here we study not only selected pulsations with very high amplitudes but also usual pulsations and try to answer the question, which pulsations’ parameters are favorable for modulation of the ionosphere.

This paper discusses the charge generation for impacts of nano- to micro-scale dust on metal surfaces at speeds below a few km/s. By introducing a model of capacitive coupling between the dust and the impact surface, we find that at such low speeds, the charge can be dominated by contact charging as opposed to plasma generation.

Plasma waves are ubiquitous in the Earth's magnetosphere. They are responsible for many energetic processes happening in Earth's atmosphere, such as auroras. In order to understand these processes, thorough investigations of these waves are needed. We use a state-of-the-art numerical model to do so. Here we investigate the impact of different spatial resolutions in the model on these waves in order to improve in the future the model without wasting computational resources.

Dust grains exist throughout our solar system. This dust is subject to destruction processes like sublimation and sputtering. Sputtering is the erosion of dust through the impact solar wind and can be very effective near the Sun. We performed calculations to find out how import the sputtering process is compared to the sublimation of dust.
Recently started spacecraft will probe the proximity of the Sun and measure the dust population. Our work will help to understand these measurements.

Rapid variations of the magnetic field measured on the ground can be used to estimate space weather risks to power grids, but forecasting the variations remains a challenge. We show that part of this problem stems from the fact that in addition to electric currents in space, the magnetic field variations are strongly affected by underground electric currents. We suggest that separating the measured field into its space and underground parts could improve our understanding of space weather.

This paper studies magnetic field fluctuations in three turbulent sheath regions ahead of interplanetary coronal mass ejections (ICMEs) in the near-Earth solar wind. Our results show that fluctuation properties vary significantly in different parts of the sheath and when compared to solar wind ahead. Turbulence in sheaths resemble that of the slow solar wind than and in terrestrial magnetosheath, e.g., regarding compressibility, intermittency and they often lack Kolmogorov's spectral indices.

Preprint under review for ANGEO(discussion: final response, 2 comments)

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This study compares trapped outer radiation belt electron fluxes to high-latitude precipitating electron fluxes during two interplanetary coronal mass ejections (ICMEs). These ICME had opposite magnetic cloud rotation. The electron response had multiple similarities and differences between the two events, indicating that different acceleration mechanisms acted in the two ICMEs. Van Allen probe data were used for trapped electron flux measurements, and POES was used for precipitating flux data.

Preprint under review for ANGEO(discussion: final response, 2 comments)

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We have applied three different methods to examine the observability, both tracking and discovery, of near-Earth objects (NEOs) by the EISCAT 3D radar system currently under construction. There are to to our knowledge no previous studies done on the expected discovery-rates of NEOs using radar systems. We show that it is feasible to regularly track NEOs and minimoons. We also show it is possible to discover new NEOs and minimoons with EISCAT 3D, something never before done with radar systems.

Predicting the strength and peak time of geomagnetic activity for the 11-year cycle is important in space weather service. The maximum aa (Ap) index is found to be well correlated to the preceding minimum. If the data point for cycle 24 were not considered, the rise time of the Ap index would be weakly correlated to the following maximum. As a result, the maximum aa (Ap) index for cycle 25 is predicted to be 26.9 ± 2.6 (17.3 ± 1.8 ± 1.2), occurring around April 2025 ± 32 months.

Preprint under review for ANGEO(discussion: final response, 2 comments)

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Numerical simulation have been used to investigate some acceleration mechanisms in order to explain the origin of the energized backstreaming ion observed at the Earth’s bow shock. This paper used test particules in two different configurations with self-consistent and fixed shock front profiles. The comparison of these two configurations allows to analyze in details the impact of the shock front non stationarity and the role of the built-up electric field in the acceleration process.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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This paper is the first to study how representation of magnetic local time (MLT) dependency of electron precipitation impacts middle atmospheric ozone response on monthly time scales. We use state-of-the-art chemistry-climate model with detailed lower ionospheric chemistry for an advanced representation of atmospheric impacts of electron forcing. We find that electron forcing that ignores MLT-dependency will still provide an accurate ozone response for long-term climate simulations.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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Electric fields in the atmosphere near dynamic aurora are important in the physics of the electric circuit within the earth's magnetic field. Oxygen ions emit light as they move under the influence of these electric fields; the flow of this emission is used to find the electric field at high temporal resolution. The solution needs two other simultaneous measurements of auroral emissions to give key parameters such as the auroral energy. The electric fields increase with brightness of the aurora.

The CSES observed ionospheric Pc1 waves near the wave injection regions in conjugate hemispheres during the recovery phase of the geomagnetic storm on 27 August 2018. The Pc1s are found to be Alfven waves with mixed polarization, propagating along background magnetic lines down into the ionosphere. We suggest the possible sources of Pc1 are EMIC waves generated near the plasmapause by the outward expansion of the plasmasphere into the ring current during the recovery phase of geomagnetic storm.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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We use satellite data to analyze the precursory anomalies of M7.1 Yushu earthquake occurred in western China through analyzing signal to noise ratio (SNR), and we use full wave model to illustrate a possible mechanism how the anomalies occurred. The results show SNR of VLF radio waves in the ionosphere decreased before Yushu earthquake. The full-wave simulation results confirm the electron density variation in the lower ionosphere will affect the SNR of VLF radio signals.

Revised manuscript under review for ANGEO(discussion: final response, 5 comments)

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Identifying ionospheric disturbances associated with an earthquake is a useful and challenging work. A new decomposition and nonlinear fitting method has been developed to analyze ionospheric total electron content (TEC) data, and to extract disturbances that are likely related to Mw7.2 Mexico earthquake occurred on April 4, 2010. We found a unique TEC depletion that occurred around the epicenter on March 25, which cannot be explained by lower atmosphere wave or geomagnetic activity forcing.

Preprint under review for ANGEO(discussion: final response, 4 comments)

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Low Latitude Aurorae (LLA) were uncommon phenomenon not well known and understood in 1780. During our historical manuscripts research of high atmospheric phenomena we came across a document reporting an observation done by the abbot Rozier in Beausejour, France, on 15/08/1780. Thanks to the accuracy of his report, we were able to confirm it was a white, with two bands structure LLA. Due to the few existing geomagnetic and solar observations it is a useful new geomagnetic activity proxy data.

Recently, the two-spacecraft mission BepiColombo was launched to explore Mercury. To measure the magnetic field precisely, in-flight calibration of the magnetometer offset is needed. Usually, the offset is evaluated from magnetic field observations in the solar wind. Since one of the spacecraft will remain within Mercury's magnetic environment, we examine an alternative calibration method. We show that this method is applicable and may be a valuable tool to determine the offset accurately.

During magnetic storms the magnetic disturbance at low latitudes becomes asymmetric, enhanced in the evening sector and reduced around morning. This has been attributed to the asymmetric ring current. Here a new 3D current system is proposed for explaining the asymmetric signal. Anti-sunward net currents at high latitude are connected at their noon and night ends to field-aligned currents that lead the currents to the magnetopause on the dawn and dusk flanks where the current closure occurs.

Forecasting the thermosphere (atmosphere's uppermost layer from 90 to 800 km altitude) is crucial to space mission design, spacecraft operations and space surveillance. Thermosphere is controlled by the Sun, through the highly variable solar EUV radiation and the solar wind. We show how two solar indices, Mg II and Ap, may be used in forecasting thermospheric density at 260 km, a very low altitude where the GOCE satellite has operated from 2009 to 2013, during the full rise of Solar Cycle XXIV.

This paper presents a comprehensive analysis of the solar event occurred on August 25, 2018. This kind of comprehensive analysis plays a key role to better understand the complexity of the processes occurring in the Sun-Earth system that determines the geoeffectiveness of solar activity manifestations. The analysis presented her shows for the first time a direct link among the solar perturbation characteristics, the magnetosphere-ionosphere system response, and the Space Weather effects.

Pulsating auroras have recently begun to be reconsidered in the context of the conditions and mechanisms driving them. This research connects one type of pulsating aurora to specific plasma waves and uses in situ plasma observations to infer the source region of this aurora. Shortcomings of the available methods of associating in situ observations with specific auroral features are outlined and a key issue is identified which challenges our understanding of pulsating aurora formation.

Revised manuscript under review for ANGEO(discussion: final response, 6 comments)

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This study developed a model of Total Electron Content (TEC) over the African region. The TEC data were derived fro radio occultation measurements done by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. Geomagnetically quiet time data during the years 2008–2011, and 2013–2017 were binned according to local time, seasons, solar flux level, geographic longitude, and dip latitude. Cubic B splines were used to fit the data for the model.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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High-energy electrons in the Earth's magnetosphere can produce operational anomalies in spacecrafts. We investigate the regular variations in these electrons as well as in Pc5 low frequency waves that are capable to generate the electrons. We find that both variables present similar periods in every solar cycle phase. We focus the analysis in the Semiannual Variation of these parameters. The shape of the observational semiannual curves correlate very well with the profiles of the main theories.

Manuscript not accepted for further review(discussion: closed, 4 comments)

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We present a study of ultra-low-frequency waves in the ionosphere and on the ground (geomagnetic pulsations). They can influence particle flux in the magnetosphere, which modify the ionosphere. However, there is no simple dependence between geomagnetic and ionospheric pulsations. We study not only selected pulsations with very high amplitudes but also usual pulsations and try to answer the question, which pulsations' parameters are favorable for modulation of the ionosphere.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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Ionospheric irregularities are a common phenomenon in the low latitude ionosphere. In this paper, we compared simultaneous observations of plasma plumes by the JULIA radar, ionogram spread F generated from ionosonde observations installed at the JRO, irregularities observed in situ by Swarm to determine whether Swarm in situ observations can be used as indicators of the presence of plasma plumes and spread F on the ground.

Revised manuscript has not been submitted(discussion: closed, 2 comments)

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In this work, the correlation between ROTI and S4 is investigated based on a derived mathematical model under the assumption of single screening model for trans-ionospheric signal propagation. The correlation between ROTI and S4 is strongly affected by the variability of the effective velocity, and the correlation coefficient is degraded when the variability increases.The scintillation index S4 depends on the ionospheric irregularities, the effective velocity and the radio propagation path.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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Solar atmospheric tides are natural oscillations of 24, 12, 8... hours that contribute to the circulation of the atmosphere from low to high altitudes. Sun heats the atmosphere periodically because, mainly, water vapor and ozone absorb solar radiation between ground and 50 km height during the day. Tides propagate upward and they can be observed in, e.g., wind field. This work presents diurnal tides observed by meteor radar which measure wind between 80 and 100 km height.

We present a comprehensive statistical study of the response of the Earth’s space environment during sheath regions preceding interplanetary coronal mass ejections. Inner magnetospheric wave activity is enhanced during sheath regions, and sheaths cause significant changes in the outer radiation belt electron fluxes on short time scales. We show that also non-geoeffective sheaths can result in a significant response.

The near-Earth environment can be divided into three main regions: the magnetosphere, the magnetosheath and the solar wind. The boundaries between the three regions being called the magnetopause and the bow shock.
The manual detection of these boundaries in the data of spacecraft orbiting the Earth is ambiguous and time consuming.
We elaborated an automatic detection method of the two bondaries. Which provides a considerable gain of time in the analysis of spacraft in-situ data.

Using the distributed source line transmission (DSLT) theory and magnetometers data, induced electrical field was calculated for the first time in a Brazilian pipeline. The corrosion rate was also evaluated using the Gummow's methodology. With different terminating impedance, the pipeline was out the safe range of operation, even for low terminating impedance. The corrosion rate was significant for strong geomagnetic storms, however it was not above the acceptable limit.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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We present a new in-situ observation of energetic electron in space obtained by a newly available particle detector. In view of the characteristic signatures in the particle flux, we attribute the observational features to the drift-resonance wave-particle interaction between energetic electrons and multiple localized ULF waves. The scenario is substantiate by a numerical calculation based on the revised drift-resonance theory which reproduced the observed particle signatures.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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Comprehensive analysis of a moderate substorm was performed with using optical observations inside the auroral oval and in the polar cap, combined with data from satellites, radars, and ground magnetometers. The onset took place near the poleward boundary of the auroral oval that is not typical for classical substorms. Data set fits to the near-tail current disruption scenario of the substorm onset. The role of the 15-min oscillations in IMF Bz component in the substorm initiation is discussed.

Manuscript not accepted for further review(discussion: closed, 10 comments)

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In-situ measurements validation is always a delicate matter of study until data are collected by a single mission. In case of different missions operating almost in the same environment (i.e. latitude, altitude, local time) it is of fundamental importance the detection of instrumental setting and algorithms to provide the best accordance among measurements. The present work aims to validate both Swarm and CSES plasma density measures for the improvements of the ionospheric models development.

Manuscript not accepted for further review(discussion: closed, 4 comments)

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Two types of temperature profile products from the FY-3 (FengYun-3) satellite system, using GNOS and VASS, together with AIRS operational Level 2 data, are used to compare and analyze gravity wave parameters. The advantages and disadvantages of these three types of temperature profile data for gravity wave parameter extraction are determined, based on three extraction methods: vertical sliding average, double-filter and single-filter.

Manuscript not accepted for further review(discussion: closed, 4 comments)

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The plasma bubbles and blobs were recorded on two successive days. The interesting is that one of the event occured in a quiet day, and the other in the main phase of a storm. The latitudinal variations of electron density at low- and middle ionosphere were used to analyze the physical factors leading to the variations in the F region and the occurrence of plasma bubbles and blobs. The work would help to understand the dominant factor accounting for the day-to-day occurrence of irregularities.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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The interaction between the Earth's environment and the electrically charged gas known as the solar wind is highly complex and has been under study for decades. We use a universal principle of physics – the relativity principle – to gain physical insight into this interaction. We apply this principle to physical processes that occur during geomagnetic storms. We clarify how the solar wind ultimately causes currents to flow between the Earth's upper atmosphere and space.

Revised manuscript under review for ANGEO(discussion: final response, 8 comments)

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Comparisons were made of ground-based ionosonde (a type of radar) observations of the ionosphere and satellite-based observations of auroral far-ultraviolet emissions to determine whether a remote sensing algorithm for determining auroral ionospheric electron densities from far-ultraviolet emissions was biased by the presence of proton precipitation, and it was found that there was no such bias.

Revised manuscript under review for ANGEO(discussion: final response, 4 comments)

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It is presented two historical aurora catalogs for Anatolia and Middle East regions at various dates to understand the past solar activity and possible physical mechanism using historical texts, chronicles and other auroral records. An unusually high auroral activity during the years around 1100 in Anatolia and Middle East is quite consistent with the past solar variability, geomagnetic field intensity and planetary climatic changes drastically impacting on the economy and human events.

Manuscript not accepted for further review(discussion: closed, 6 comments)

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In a context of climate change, the wind energy sector has seen a very sharp growth requiring accurate forecasts. Air density is a key variable in the wind energy modeling as it can make the power output varies by almost 20 %. In this paper, a numerically low-cost method is evaluated. This method improves the wind energy modeling by more than 15 % and by almost 40 % when the atmospheric conditions are far from the standards atmospheric conditions used to produce the wind turbine power curve.

Manuscript not accepted for further review(discussion: closed, 4 comments)

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To correct the NRLMSISE-00, more than 15 years of satellite atmospheric density data is used at 20–100 km. Based on the differences between model and observation data, a spatiotemporal correction function is proposed. The correction function has a significant improvment to the model. It can provide more reliable density data for scientific research and engineering fields.

Distributions of proton fluxes in the Earth's Radiation Belts (ERB) are well studied and the NASA empirical models constructed for them. For heavier ERB ions (helium, oxygen, etc.) there are only fragmentary data and no sufficiently complete and reliable empirical models. Using our methods, these data one can streamlined, linked to each other and get a regular picture that has a simple physical meaning.

Revised manuscript has not been submitted(discussion: closed, 9 comments)

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The morphological characteristics of ionospheric response to tropical cyclone Debbie passing eastern Australia in 2017 is investigated by GPS and ion sounder. The results agree with the previous viewpoint that tropical cyclone can trigger ionospheric disturbance. Considering the influence from the geomagnetic and solar activity, the turbulent top movement theory is utilized to explain how tropical cyclone causes ionospheric irregularity and further triggers ionospheric scintillations.

The Brazilian INPE-UFSM NANOSATC-BR CubeSats Development Program consists of two CubeSats, NANOSATC-BR1 (1U) & NANOSATC-BR2 (2U). NANOSATC-BR2 is expected to operate in orbit for at least 12 months, while NANOSATC-BR1 this year has completed more than four years in orbit operation. This paper focuses on the future development of NANOSATC-BR3 & NANOSATC-BR4, in a partnership with the UFSM's Aerospace Engineering Course and on the launching of NANOSATC-BR2.

Revised manuscript under review for ANGEO(discussion: final response, 9 comments)

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Winds in the Earth's upper atmosphere cause magnetic and electric variations both at the ground and in space all over the Earth. According to the model of entangled dynamos the true cause is wind differences between regions in the northern and southern hemisphere that are connected by the Earth's dipole-like magnetic field. The power produced in the southern dynamo heats the northern upper atmosphere, and vice versa. The dynamos exist owing to this entanglement, an analogy to quantum mechanics.

Manuscript not accepted for further review(discussion: closed, 5 comments)

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By shooting away electrons from a spacecraft, it will deplete its surrounding electrons and create a large range of positively charged plasma, which will couple with an even larger range of the ambient plasma, and be accelerated or decelerated according to the relative speed between the craft and its ambience. A spacecraft can use the solar wind, artificial particle beam, or cosmic jet to achieve very high interstellar travelling velocity, or brake at the destination, with no propellant.

Preprint under review for ANGEO(discussion: final response, 8 comments)

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Local occurrence rate (LOR) is defined to clarify the characteristics of ionospheric irregularities together with monthly occurrence rate (MOR) at 20–29° N in solar minimum, medium and maximum years of 2008, 2003 and 2014. MOR of irregularities in May/June is larger than that in equinoxes, which is different with the equatorial plasma bubbles. LOR shows that the irregularities at 26–29° N in May/June are more frequently happened and have smaller spatiotemporal scales than those at lower latitudes.

Preprint under review for ANGEO(discussion: final response, 2 comments)

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The composition of the upper atmosphere has been difficult to measure with localised observations relying on spacecraft or sub-orbital rockets or measurements of airglow from ground-based observatories. The height profile of ionisation within the neutral upper atmosphere is influenced by the composition of the neutral gas. We present a method for determining the neutral upper atmosphere composition from measurements of the ionisation profile, and compare these with spacecraft measurements.

The performance of IRI-2016 model in simulating GPS-TEC is assessed based on various statistical tools during two distinct solar activity periods. In particular, the categorical metrics used in the study to assess the the performance of the empirical and climatological IRI-2016 model at the margins of TEC distribution reveal remarkable skill of the model in simulating the observed tails of TEC distribution, which is by far better than accurately simulating the observed climatology as designed.

When studying the Rayleigh-Taylor instability (RTI) in the ionosphere, I found that the physical description of RTI in ionosphere attribute the growth of RTI to charge accumulation, however, the current continuity equation was used during the calculation of the linear growth rate. Also, the linear growth rate widely used tends to infinity when the collision frequency tends to zero. In this paper, we derived the linear growth rate of RTI and rectified the physical description of the RTI process.

Some systems, such as Over the Horizon Radars, use the ionosphere as a reflector for HF radio signals. In this work, HF propagation through the ionosphere is studied for different Earth’s magnetic field configurations during reversals using a numerical ray tracing technique. Our purpose is to highlight possible effects of dipole decrease, which is currently ongoing, on electromagnetic wave propagation through the ionosphere.

Manuscript not accepted for further review(discussion: closed, 7 comments)

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The latest research suggests that there could be a relationship between geomagnetic field variations and seismic events in different parts of the planet. These variations have been found in both ground-level magnetometers and satellites studying the ionosphere. The magnetic variations are similar between the earthquakes in Chile (2010, 2014, 2015) and the one in Mexico 2017. Therefore, the use of magnetic variations at ground level or ionospheric could show seismic precursors.

Although solar eclipses often occur above Indonesia, observations on ionospheric dynamics during solar eclipse have not been widely carried out. The results contained in this research, such as information related to the decrease of total electron conrent (both temporally and spatially) and scintillation behavior when facing a unique phenomenon such as solar eclipse can be used as a reference for the next solar eclipse not only for Indonesia but also for another region.

Observations of ﬂapping current sheet in the magnetotail are presented to reveal their intrinsic excitation mechanism induced by alternating north-south asymmetric ion populations in the sheet center. The results suggest that nonadiabatic ions play a substantial role to determine current sheet dynamics, both its bulk mechanical instability and current profiles.

During observations of the electromagnetic waves onboard Vernov satellite in 2014 some interesting phenomena were discovered. They are connected to non-linear effects in wave activity of the type of two or three wave decays as well as splitting into two wave structures. Whistlers with specific unusual temporal structure of swallowtail type were observed. It was shown that such signals can be caused by seismic activity.

Turbulence dissipation rate has inter-annual variations and follows a lognormal distribution. The magnitudes of turbulence detected by radiosonde and radar are roughly comparable. Turbulence cannot predicted by instabilities well but trends to be vigorous under the instability condition. The propagating gravity waves in the lower atmosphere can enhance atmospheric instabilities, and the temporal variations of waves can roughly estimate the turbulence dissipation rate at different height.

Manuscript not accepted for further review(discussion: closed, 4 comments)

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Decidated to the combined analysis of space weather data (geomagnetic activity, cosmic ray secondaries and ionospheric data) obtained during the September 2017 solar flares and geomagnetic storms, this study is an attempt to construct a technique for circumterrestrial physical data analysis in order to analyze various space weather effects and obtain new mutually supportive information during major space weather events on different phases of geomagnetic storm evolution.

We have over viewed an algorithm which can be used to estimate ionospheric delays of GPS observations using single GPS receiver using a spherical ionospheric shell model. This Algorithm depends on the geometry-free carrier-phase observations after detecting cycle slip. The ionospheric estimation in this algorithm is performed by means of Sequential least-squares adjustment. This study is performed on ten IGS stations, and results of the ionosphere delay was compared with GAPS software results.

The comparison of geomagnetic active and quite events of double substorm onsets responsive to IMF variations shows that the occurrence sequence of all required substorm signatures looks the same and not different for small and large Kp. Double substorm onsets responsive to IMF variations can be characterized with two-stage magnetic dipolarizations in the magnetotail, two auroral breakups of which the first occurring at lower latitudes than the second, and two consecutive Pi2-Ps6 band pulsations.

Manuscript not accepted for further review(discussion: closed, 4 comments)

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In this article, the Semiannual Variation is recognized in electron fluxes of the outer radiation belt using Van Allen Probes data. The maxima near the equinoxes are clearly seen but the the maximum of the March equinox appears delayed one month from the theories prediction. Also, the Semiannual Variation is detected only in a narrow energy range: electron fluxes with energies between the MeV to tens MeV.

The current paper evaluates the ionospheric correction by Global Ionospheric Maps, GIM, provided in (IONEX) files produced by International GNSS Services “IGS”. The evaluation is done based on investigating the effect of given GIM ionospheric correction on kinematic relative positioning solution. The evaluation has been performed on several baselines with different lengths in Egypt.

The ionosphere varies the most over the Northern hemisphere. This is called the annual anomaly. Ionospheric models, such as the International Reference Ionosphere (IRI), underrepresent the anomaly. The ionosphere affects radio waves, so it is important to always improve these models. We show that it is considering the ionosphere's hemispheric behavior is required to improve IRI. We suggest that the annual anomaly is caused by processes which differ over each hemisphere.

Manuscript not accepted for further review(discussion: closed, 9 comments)

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Studies on TEC variations at Birnin-Kebbiin Northern Nigeria during the ascending and maximum phases of solar cycle 24 have been carried out. The Receiver Independence Exchange (RINEX) GPS data files were downloaded daily from NIGNET website (http://www.nignet.net) and processed using Bernese software and GPS TEC analysis software. GPS TEC obtained from the TEC analysis software is the STEC. VTEC is calculated from the daily values of STEC. Higher TEC during the daytime than nighttime were observed.

Manuscript not accepted for further review(discussion: closed, 8 comments)

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This paper captures the signature of heavy rainfall events using the 2-d-/4-d water vapour information derived from GNSS measurement in Hong Kong. The paper first analyzed the relationship between the two-dimensional (2-d) precipitable water vapour (PWV) and rainfall. And then, the four-dimensional (4-d) variations of atmospheric water vapour derived from the GNSS tomographic technique are discussed, especially in the vertical irection. Finally, some interesting results are found and presented.

Manuscript not accepted for further review(discussion: closed, 4 comments)

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Maximum upper atmospheric turbulence results in the mesosphere from convective and/or dynamic instabilities induced by gravity waves. For the first time, by comparing the vertical accelerations induced by wind shear and the buoyancy force, it is shown that the critical Richardson number can be estimated. This new approach, for the first time, makes it is possible to establish and estimate the temperature gradient impact on dynamic instability development.

The disturbance in geomagnetic field is quantified using the newly introduced Vertical Variance (VV) method. Latitude profile of geomagnetic disturbance for 34 stations across the Earth is developed. The latitude profile developed is employed to determine the latitudes which are subject to high geomagnetic disturbance. The geomagnetic disturbance however falls singularly at the auroral latitudes. This singular variation is explored and investigated.

Magnetic field of the Earth is continuously measured by a network of observatories. It implies application of mathematical and computational technologies for geomagnetic data processing. Actual conditions in which observations are performed should be also considered. Effective identification of noise and elimination of its influence on final data is an important part of the data processing. An original approach for magnetic data processing and some partial results are discussed in this paper.

The ion to electron temperature ratio is a good indicator of the processes involved in the plasma sheet. We theoretically estimate how patchy magnetic reconnection electric field accelerates ions and electrons differently. As particles are transported earthward by BBFs after reconnection, the reflection of electrons from the ionosphere and subsequently multiple non-adiabatic accelerations at the reconnection site can explain the observed lower temperature ratios closer to the Earth.